1. Field of the Invention
The present invention relates to a solid-state imaging device, and more particularly, to a solid-state imaging device used for an imaging apparatus, for example, a digital still camera.
2. Description of the Related Art
In recent years, a solid-state imaging device in which multiple CCDs or CMOS elements are two-dimensionally arranged has been used for a digital video camera and a digital still camera. The solid-state imaging device is manufactured as follows. A photoelectric conversion unit and a diffusion unit are formed in a substrate by impurity introduction, for example, ion implantation. After that, films are deposited on the substrate and processed to form wiring parts and insulating films. Incident light entering the solid-state imaging device is absorbed in the photoelectric conversion unit and converted into charges. The charges are stored in the photoelectric conversion unit. When a total amount of the stored charges is detected, a signal corresponding to an intensity of the incident light may be obtained.
However, when a penetration length of the incident light is longer than a length of the substrate, the incident light is not sufficiently absorbed in the photoelectric conversion unit, and thus a part of the incident light passes through the substrate. Therefore, the part of the incident light cannot be converted into a charge signal, and hence light use efficiency is reduced. In order to solve such a problem, an imaging apparatus in which the light passing through the substrate is reflected toward the photoelectric conversion unit again has been proposed in Japanese Patent Application Laid-Open No. 2007-027604. Note that, the penetration length of the incident light indicates a propagation length to reduce a light intensity to 1/e of the incident light intensity by absorption loss.
However, as illustrated in FIG. 10, in a reflecting film structure of the imaging apparatus described in Japanese Patent Application Laid-Open No. 2007-027604, incident light beams 930 refracted by a micro-lens 910 are reflected on a reflecting film 901 and propagate to adjacent pixels. Therefore, noise, (e.g., crosstalk) is caused by the reflected light beams, and hence an S/N ratio of an image is reduced.